1. Field of the Invention
The present invention relates to carbon nanocapsules, and more particularly to a carbon nanocapsule supported catalysts.
2. Description of the Related Art
A carbon nanocapsule is a polyhedral carbon cluster constituted by having concentric multi-layers of closed graphitic sheet structure. The diameter of a carbon nanocapsule is about 3-100 nm. There are two types of carbon nanocapsules: hollow and metal-filled. The center of a hollow carbon nanocapsule is leaving a nanoscale cavity, while that of a metal-filled nanocapsule is filled with metals, metal oxides, metal carbides, or alloys.
Carbon nanocapsules were first discovered with carbon nanotubes in 1991, in the process of producing carbon nanotubes. Due to the strong van der Waals force between carbon nanocapsules and carbon nanotubes, carbon nanocapsules are not easily isolated from the carbon nanotubes. In addition, the amount of carbon nanocapsules produced with carbon nanotubes is sufficient only for structural observation under an electron microscope, thus the application thereof is limited.
With continuous research, processes producing high-purity hollow carbon nanocapsules as well as magnetic metal-filled carbon nanocapsules have been developed. (Please refer to U.S. patent application Ser. No. 10/255,669 and 10/329,333) With their special hyperfullerene structure and optoelectronic properties, polyhedral carbon nanocapsules is brought about by well-developed graphitic structure, with high impact strength, electric and heat conduction and surface area, are suitable for use as catalyst supports.
Materials including aluminum oxide, Zeolite, silicon oxide, magnesium oxide, carbon black and carbon nanotubes are generally used as supports for catalytic metal particles. With different supports, metal particles may have different catalytic properties. Therefore, serious consideration must be given to the objects of catalysis, the catalytic environmental conditions, and compatibility between catalysts and supports when selecting a suitable support.
Carbon materials such as carbon black and carbon nanotubes have been used as supports for catalytic metal particles, and various studies regarding their catalytic effects have been performed. Studies regarding the use of a carbon nanocapsule as a catalyst support, however, are lacking.